From Linux Man Pages
exit - cause normal process termination
SYNOPSIS
#include <stdlib.h>
void exit(int status);
DESCRIPTION
The exit() function causes normal process termination and the value of status & 0377 is returned to the parent
(see wait(2)).
All functions registered with atexit() and on_exit() are called, in the reverse order of their registration. (It
is possible for one of these functions to use atexit() or on_exit() to register an additional function to be exe-
cuted during exit processing; the new registration is added to the front of the list of functions that remain to
be called.)
All open streams are flushed and closed. Files created by tmpfile() are removed.
The C standard specifies two constants, EXIT_SUCCESS and EXIT_FAILURE, that may be passed to exit() to indicate
successful or unsuccessful termination, respectively.
RETURN VALUE
The exit() function does not return.
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001.
NOTES
It is undefined what happens if one of the functions registered using atexit() and on_exit() calls either exit()
or longjmp().
The use of EXIT_SUCCESS and EXIT_FAILURE is slightly more portable (to non-Unix environments) than that of 0 and
some non-zero value like 1 or -1. In particular, VMS uses a different convention.
BSD has attempted to standardize exit codes; see the file <sysexits.h>.
After exit(), the exit status must be transmitted to the parent process. There are three cases. If the parent has
set SA_NOCLDWAIT, or has set the SIGCHLD handler to SIG_IGN, the status is discarded. If the parent was waiting
on the child it is notified of the exit status. In both cases the exiting process dies immediately. If the parent
has not indicated that it is not interested in the exit status, but is not waiting, the exiting process turns
into a "zombie" process (which is nothing but a container for the single byte representing the exit status) so
that the parent can learn the exit status when it later calls one of the wait() functions.
If the implementation supports the SIGCHLD signal, this signal is sent to the parent. If the parent has set
SA_NOCLDWAIT, it is undefined whether a SIGCHLD signal is sent.
If the process is a session leader and its controlling terminal is the controlling terminal of the session, then
each process in the foreground process group of this controlling terminal is sent a SIGHUP signal, and the termi-
nal is disassociated from this session, allowing it to be acquired by a new controlling process.
If the exit of the process causes a process group to become orphaned, and if any member of the newly orphaned
process group is stopped, then a SIGHUP signal followed by a SIGCONT signal will be sent to each process in this
process group.
RELATED
_exit(2), wait(2), atexit(3), on_exit(3), tmpfile(3)
CATEGORY